longer stroke torque debate

[c00nhunterjoe]

When discussing why the 440 makes more horsepower and torque then a 383, the answer is always "because it has a longer stroke" there seems to be no room for discussion here and I am here to ask for proof beyond "because thats how it is" Show me the evidence that backs up your statments that the 3.75 stroke is the reason for the power instead of the fact that it is 57 cubic inches larger.


    Are we all ready for a little fun and history? ok, lets go
the 383 went through a bunch of changes and had various outputs over the years. Their best rating was 335\435 in 1969. Now before we even begin to discuss the 440, lets compare it to something a little more similar that most guys forget about; the 426. No, not the infamous hemi, the wedge 426. Now calm down, Im not talking about the max wedge, because we all know they were 13:1 monsters rated at 425 hp with different heads altogether. I am talking about the 426 street wedge from 1964 and 65'. She has the same 4.25 bore as the 383, has a similar cam profile, used the same 516 heads (in most cases) as the 383's did and ran a 4 barrel carb. The biggest difference was the crank -3.75 stroke. They were built slightly hotter then the 383, but it is a pretty close comparison.
    The 64-65 426 street wedge was rated at 365\470. Now before we all start yelling about the power increase is all because of the stroke, lets do a little math. 1st of all, the street wedge was rated at 11:1 compression, a full point about the 383's best year. On average, 1 point of compression is worth a 5% increase in power output, but for this discussion lets say 4% which comes out to about 14 hp, 19 ft lbs. That number alone brings our 365 hp down to 351 and our torque from 470 down to 351. Hmmmm, does anyone else see a trend starting? That means that our power increase by increasing the 383 stroke from 3.375 to 3.75 is corrected at 16 hp and 16 ft lbs.
    Now im sure there are already heads rolling so lets do it again. Lets throw the 4% compression number out the window and assume that there is ZERO increase in hp\tq by going from 10:1 to 11:1. So we have a 426 rated at 365\470 and a 383 rated at 335\435. Time for a little more math.... The 426 is 43 cubes bigger then the 383, yet the 426 only makes 30 more horsepower and 25 ft lbs more torque..... hmmmmmm interesting facts, isnt it???
    Alright, alright, Dodge scrapped the 426 street wedge after only 2 years, so it must have been a junk motor. So in comes the 440 powerhouse. With a single 4 barrel, better flowing heads (906 vs 516) she was only rated at 350\480 in 1969. If you got a better cam it was supposedly good for 375\480, and the 6 packs were rated at 390\490 if memory serves me. But we have to throw the 6 pack out since the 3 2's when corrected for cfm conversion actually comes out to 900+ cfm compared to the little single 4 on a 383. Ok, for arguements sake, lets just stick with the 375 number since i dont want to be drawn into another debate over why the 350hp isnt valid...hahaha. Anybody ready for simple math? even with the superior heads, the 440 only produces 40 more horsepower and 45 ft lbs more torque and takes 57 more cubic inches to do it!! If we take the lesser rated cam that is actually closer to the 383, then the number is only 15 horspower more.
    Here is another mind blowing math fact. The 375hp 440 produces .85 hp\cubic inch while the 335 horse 383 produces .87 hp\cubic inch. The 365 horse 426 makes .85 hp\cubic inch also. Does ANYONE else follow the pattern???

    In conclusion, i would like to be sure to state that I am in NO WAY bashing the 440. There is NO REPLACEMENT FOR DISPLACEMENT. Displacement is the key, not necessarily stroke as shown in the facts above. I also realize that i am a nobody, so i challenge you do a little research on your own. There are plenty of articles from racers that will back up my story, the info is out there. I am just one guy that has researched, built and played alot and come to my own conclusions from the facts that i have been presented, and come across on my own. I am also not saying that you cant make power with stroke because that would be an incorrect statement. But simply saying adding stroke is the key, is incorrect. i hope you enjoyed my story\rant, and I look forward to the responses. 

[Cooter]

440 @ 4.320" bore and 3.750 stroke Vs 400@ 4.380" bore and 3.350 stroke...
If bore played as much a role as one would have us believe, the 400 with it's much larger piston should produce much more torque, everything being equal. However as with many theories in the real world,  it just "don't".

Like stated before using the SBC. 350 C.I @4.00" bore.3.80 stroke.
and a 3.750 stroke and no more bore, yet massive gain in torque just by adding more stroke.
This is the theory behind strokers. ...add more twisting force (which is torque) you get more cubes, but more often a massive HP to torque ratio favoring torque. 

[c00nhunterjoe]

the 400 was an 8:1 engine with a garbage cam and built for smog. its no wonder it only made 250 hp. but the 440s of the same era made less in some cases. you are trying to compare a smog 400 to a muscle era 440. apples to oranges again. check your data before claiming the 440 makes more then the 400 in the smog years.

here is a simple link to the power. there are plenty of charts and service manuals available.
http://www.mymopar.com/enginespecs.htm

[Cooter]

Must have missed where I clearly stated 'everything else being EQUAL'...Please read before you ask me to check my data..

[c00nhunterjoe]

Clearly, if everything else was equal in your 400 to 440 comparison, it would have made more power, but they were not equal and therefore the 400 did not make more power.

Here is a snip from a hotrod article where the build was equal other then swapping bore vs stroke to acheive a certain cubic inch.

[c00nhunterjoe]

Like stated before using the SBC. 350 C.I @4.00" bore.3.80 stroke.
and a 3.750 stroke and no more bore, yet massive gain in torque just by adding more stroke.
This is the theory behind strokers. ...add more twisting force (which is torque) you get more cubes, but more often a massive HP to torque ratio favoring torque. 

this portion is exactly what i portrayed in the origonal post where mopar essentially took the 383, changed only the stroke, and only increased torque by 25 ft lbs.

[Challenger340]

"Engine Dynamics"..... could become an extremely involved subject for this forum ?

Everything.... and there are ALOT of other "things"...... affects EVERYTHING else, with very limited "linear" mathematical controls being viable.

I don't understand your Torque question though ?
For a given angularity same/same..... 100 Lbs "push".... on a 3.38" lever = 338 lbs/inch Torque
whereas,
                                            .......100# "push".... on a 3.75" lever = 375 lbs/inch Torque

The above speaks nothing to any other mitigating factors.

 

[Cooter]

Exactly.


Tis true factors such as parasitic loss (piston side loading) plays a certain rule in torque as well as HP, but
comparing a 426 RB To a LB 383 is apples and oranges.

I'm thinking a LB 383 (like the one we built at F&P Performance) with a 440 Crank, cranked  out way more torque than 25 more ft. Lbs. With everything (albeit performance mods) being the exact same save for more stroke. It was more like 70 more.

[c00nhunterjoe]

"Engine Dynamics"..... could become an extremely involved subject for this forum ?

Everything.... and there are ALOT of other "things"...... affects EVERYTHING else, with very limited "linear" mathematical controls being viable.

I don't understand your Torque question though ?
For a given angularity same/same..... 100 Lbs "push".... on a 3.38" lever = 338 lbs/inch Torque
whereas,
                                            .......100# "push".... on a 3.75" lever = 375 lbs/inch Torque

The above speaks nothing to any other mitigating factors.

 

I agree and that goes along with my point. Stroke is only a part of the overall equation.
   My origonal post was to simply show that by changing NOTHING in the engine but the crank, you wouldnt have the instant "torque monster" illusion that is always painted on the internet and this forum.  I dont see how cooter can claim that my 426 wedge compared to the 383 is apples to oranges? Exact same bore, heads, same flowing intake, similar cams and
Carbs, only real difference isthe stroke. I see no closer comparison to show the difference in ONLY changing the stroke of the engine.
    Most stroker builds that we see on here have huge gains over stock. but not just because they drop a big swinging crank in. They put nice heads, big cams, fancy intakes.... you get the picture. Its the total package that makes the power, not just the crank.
   

[Cooter]

1970 383 @ 9.5:1
425 lb. Ft.


1962 413 @ 9.5:1
With smaller valves, sh**ty ports, (compared to 906) and way less bore....
495 lb.ft.

[Challenger340]

Ports play a far larger role in Torque than many would believe ?
just as "Quality" of the air/fuel mixture to incipient flamefront propagation does..... all timing maximum "pressures" to occur at the optimal point in crank rotation, and for best duration of burn.(and just the opposite when the "low octane" Nitrous dorks try drowning the flamefront so they can be "pump gas" HERO's)

And as far as internal combustion has come, still so many Engine fallacies out there ?
just like the old .050" is "optimal" quench ?
Which I would never argue, it is about best on a low ratio 4.00" Bore.....
and,
No point trying to educate anyone else on other applications ? But if anybody gets time.... start thinking about that .050" quench used across the board OK ?

[c00nhunterjoe]

1970 383 @ 9.5:1
425 lb. Ft.


1962 413 @ 9.5:1
With smaller valves, sh**ty ports, (compared to 906) and way less bore....
495 lb.ft.

Lol, you are trying to split hairs now, and to set the record straight, the 62 413 with 495 ft lbs was the 375 horse model that had 2 4's on it.... not even close to apples and apples.

[c00nhunterjoe]

Ports play a far larger role in Torque than many would believe ?
just as "Quality" of the air/fuel mixture to incipient flamefront propagation does..... all timing maximum "pressures" to occur at the optimal point in crank rotation, and for best duration of burn.(and just the opposite when the "low octane" Nitrous dorks try drowning the flamefront so they can be "pump gas" HERO's)

And as far as internal combustion has come, still so many Engine fallacies out there ?
just like the old .050" is "optimal" quench ?
Which I would never argue, it is about best on a low ratio 4.00" Bore.....
and,
No point trying to educate anyone else on other applications ? But if anybody gets time.... start thinking about that .050" quench used across the board OK ?

More great points. It comes down to your total package, not just 1 component of the build.

[Cooter]

Made no difference. I'll enlighten you. Those twin fours were damn near 400 CFM each.
ok, I'll give you that 650 Holley on that 70 383 'might' be 150 CFM behind.
Take away 25 lb. Ft. Still kicked that short stroker's ass with less piston.....


Btw: never mind the 383 had more.....better heads, bigger valves, AND more piston.
I know the 383 is what you root for (underdog), but apples to apples (as after considering ALL the 383 had over the 413, one has to understand. Torque goes UP from the starting point with additions.

[/quote]

Lol, you are trying to split hairs now, and to set the record straight, the 62 413 with 495 ft lbs was the 375 horse model that had 2 4's on it.... not even close to apples and apples.
[/quote]

[c00nhunterjoe]

Made no difference. I'll enlighten you. Those twin fours were damn near 400 CFM each.
ok, I'll give you that 650 Holley on that 70 383 'might' be 150 CFM behind.
Take away 25 lb. Ft. Still kicked that short stroker's ass with less piston.....


Btw: never mind the 383 had more.....better heads, bigger valves, AND more piston.
I know the 383 is what you root for (underdog), but apples to apples (as after considering ALL the 383 had over the 413, one has to understand. Torque goes UP from the starting point with additions.

Ok, then if that 413 was so crippled and made 375/495, then why does a 440 with "all the better parts" make less hp and tq then the 413?


Ya know what, nevermind, the point has been proven that stroke alone is not the answer, you need the total package, and your 413 scenario also proves that with the 2 4's and intake style.

[cdr]

this is a dyno run from my old dyno & 94 ci harley  ,this is an example of how intake runner length can affect torque, the pink line is a 22 in long runner,
the blue is a 12 in runner everything else is the same & it was tuned for the best out put with both set ups.

[XH29N0G]

I really appreciate this discussion.  And am about to dive in like a fool with a thought that may or may not be right.  (I have not seen it explained this way, but it seems to make sense to me)  Thinking just about stroke and bore for now, (no resistance or geometry),

Say we have 2 engines with the same displacement.

One has a stroke twice as long as the other.  This means that if the force pushing on the crank is the same, the longer stroke will have twice the torque as the shorter stroke.  

This I agree with, but to keep the same displacement the piston area of the one with the longer stroke needs to be 1/2 that of the one with the shorter stroke.  And I think this will affect the amount of force that is transferred to the piston, then down the rod, and to the place where it connects to the crank.  

My guess is that this means that the force on the piston of the shorter stroke engine will be twice as much as for the longer stroke engine if the pressure in the combustion chamber is the same and all else is equal.

I think this factor of two for force will basically cancel the factor of 2 for the stroke on torque.  Meaning they would have the same torque.  

This would suggest to me that the torque may be largely controlled by displacement and then other factors (how much fuel is burned, how it burns, how much resistance there is to turn the engine over, the inertia of the parts, etc.....)

I am curious to hear other's thoughts on this idea.

[c00nhunterjoe]

Let me be the 1st to say that if you are starting from scratch, whether its a 383, 400, or 440 block, build a stroker of some form. The cost of the rotating assemblies makes it a no brainer. With increased stroke comes cubes, with cubes comes power no matter how you look at it. Stroke is very important, as is bore, head flow, cam... etc etc... my whole purpose of this topic was that if you have a solid 383, you do NOT have to scrap it for a 440 to make power.

[moparnation74]

my whole purpose of this topic was that if you have a solid 383, you do NOT have to scrap it for a 440 to make power.

I am a fan of 383's, 440's, and 426's.  So I am not biased here. 

I agree with his statement above and he is correct.

[Challenger340]

Let me be the 1st to say that if you are starting from scratch, whether its a 383, 400, or 440 block, build a stroker of some form. The cost of the rotating assemblies makes it a no brainer. With increased stroke comes cubes, with cubes comes power no matter how you look at it. Stroke is very important, as is bore, head flow, cam... etc etc... my whole purpose of this topic was that if you have a solid 383, you do NOT have to scrap it for a 440 to make power.

With increased stroke comes cubes, with cubes comes power no matter how you look at it.

That depends ?
Gasoline when burned, gives off heat measured in "BTU's", or British Thermal Units of heat "energy".
The amount of "power".... is a finite number relative to the MAXIMUM quantity of BTU's that can be delivered by a given Head Flow, and burned efficiently.

For a given "Flow" available with a set of Heads, call it "X" amount of BTU's that Head can deliver..... you can only extract "power" from the burning of that "X" amount.
No increase in STROKE by itself, will ever change the "amount" a Head will Flow, or the BTU potential that Head can deliver
Stroke.... can only change the rate of "demand" for the Head Flow available, or how the Head Flows to it's potential.(lower rpm by demanding more.... sooner, or increasing Torque through increased port velocity/mixture, but then going "sonic" @ rpm sooner)

I would agree that Stroke, can make better use of available Head Flow, within a more "useable" rpm range for many combinations, but depending upon the definition of "power", as it relates to extended "averages" versus "peaks", I would suggest potentially a robbing peter to pay paul rpm scenario exists, all things being equal.

[Cooter]

Made no difference. I'll enlighten you. Those twin fours were damn near 400 CFM each.
ok, I'll give you that 650 Holley on that 70 383 'might' be 150 CFM behind.
Take away 25 lb. Ft. Still kicked that short stroker's ass with less piston.....


Btw: never mind the 383 had more.....better heads, bigger valves, AND more piston.
I know the 383 is what you root for (underdog), but apples to apples (as after considering ALL the 383 had over the 413, one has to understand. Torque goes UP from the starting point with additions.

Ok, then if that 413 was so crippled and made 375/495, then why does a 440 with "all the better parts" make less hp and tq then the 413?


Ya know what, nevermind, the point has been proven that stroke alone is not the answer, you need the total package, and your 413 scenario also proves that with the 2 4's and intake style.

Obviously, you're one of those that think if fifty people agree with a certain post, it must be true.
I beg to differ. It only proves there's fifty "sheeple" that agree, be it right or wrong.
I'm not debating whether or not adding additions makes MORE torque, I'm simply saying that increasing stroke without increasing anything else has, will, and will continue to increase total torque output.

You asked about the 440 and 413. Ok, in your own words, (since apples and apples is your thing) let's give the 440 the same 'Ram induction' as the 413. As Charlie posted, runners increase torque.
the 440 will be as close if not surpass the 413. I was simply using the handicap with the 383/413 as it would be unfair to compare the higher compression 413 to a low comp 400. Even with less piston.
as stated, compression (piston the same size) effects how hard you shove down on that 3.750 lever.

[c00nhunterjoe]

Made no difference. I'll enlighten you. Those twin fours were damn near 400 CFM each.
ok, I'll give you that 650 Holley on that 70 383 'might' be 150 CFM behind.
Take away 25 lb. Ft. Still kicked that short stroker's ass with less piston.....


Btw: never mind the 383 had more.....better heads, bigger valves, AND more piston.
I know the 383 is what you root for (underdog), but apples to apples (as after considering ALL the 383 had over the 413, one has to understand. Torque goes UP from the starting point with additions.

Ok, then if that 413 was so crippled and made 375/495, then why does a 440 with "all the better parts" make less hp and tq then the 413?


Ya know what, nevermind, the point has been proven that stroke alone is not the answer, you need the total package, and your 413 scenario also proves that with the 2 4's and intake style.

Obviously, you're one of those that think if fifty people agree with a certain post, it must be true.
I beg to differ. It only proves there's fifty "sheeple" that agree, be it right or wrong.
I'm not debating whether or not adding additions makes MORE torque, I'm simply saying that increasing stroke without increasing anything else has, will, and will continue to increase total torque output.

You asked about the 440 and 413. Ok, in your own words, (since apples and apples is your thing) let's give the 440 the same 'Ram induction' as the 413. As Charlie posted, runners increase torque.
the 440 will be as close if not surpass the 413. I was simply using the handicap with the 383/413 as it would be unfair to compare the higher compression 413 to a low comp 400. Even with less piston.
as stated, compression (piston the same size) effects how hard you shove down on that 3.750 lever.

Lol, you pretty much just agreed with me. I never said toeque wouldnt go up. I said stroke alone while changing NOTHING else, will not create a monster torque motor compared to the smaller stroke equivalent.
   Yes, the long runner intake on the 440 would definatly boost and probably surpass the 413, i completely agree Just asit would on the 383, although i am not saying the 383 would outperform the 440. I have never said that.

[c00nhunterjoe]

Let me be the 1st to say that if you are starting from scratch, whether its a 383, 400, or 440 block, build a stroker of some form. The cost of the rotating assemblies makes it a no brainer. With increased stroke comes cubes, with cubes comes power no matter how you look at it. Stroke is very important, as is bore, head flow, cam... etc etc... my whole purpose of this topic was that if you have a solid 383, you do NOT have to scrap it for a 440 to make power.

With increased stroke comes cubes, with cubes comes power no matter how you look at it.

That depends ?
Gasoline when burned, gives off heat measured in "BTU's", or British Thermal Units of heat "energy".
The amount of "power".... is a finite number relative to the MAXIMUM quantity of BTU's that can be delivered by a given Head Flow, and burned efficiently.

For a given "Flow" available with a set of Heads, call it "X" amount of BTU's that Head can deliver..... you can only extract "power" from the burning of that "X" amount.
No increase in STROKE by itself, will ever change the "amount" a Head will Flow, or the BTU potential that Head can deliver
Stroke.... can only change the rate of "demand" for the Head Flow available, or how the Head Flows to it's potential.(lower rpm by demanding more.... sooner, or increasing Torque through increased port velocity/mixture, but then going "sonic" @ rpm sooner)

I would agree that Stroke, can make better use of available Head Flow, within a more "useable" rpm range for many combinations, but depending upon the definition of "power", as it relates to extended "averages" versus "peaks", I would suggest potentially a robbing peter to pay paul rpm scenario exists, all things being equal.

Lol, what happened to not getting into engine dynamics? I agree with everything you said, my statement was directed at the majority of the stroker builds we see on this website.

[BSB67]

I honestly did not read all of the posts all of the way through.  Not really sure what the point is but size does matter.  Personally I don't get hung up on stroke, but stroke is an easy way of making a motor bigger.

We can spend all kinds of time talking about air flow and BTUs, which is all spot on, but what does it all really mean.  Does anyone really care that if you can achieve B1 head flow on a 273 cu in engine and spin it to 13,000 rpm it can make 700 hp?

Despite all of the talk about torque, torque, torque, I'll take hp any day, because my preference is to be faster.  Larger bore has a better potential to make more power.

Generally speaking, the cost to make XX hp/cubic inch, is about the same from motor to motor.  So to make about 273 hp from a 273 cubic engine will cost the same as to make 440 hp from a 440 cubic engine.

[69wannabe]

 

[polywideblock]

so where does the oddball RB 383 come into this ?

if you built 2 identical motors except for one being the RB 383 and the other being  a B 383 would they make the same power 

[c00nhunterjoe]

so where does the oddball RB 383 come into this ?

if you built 2 identical motors except for one being the RB 383 and the other being  a B 383 would they make the same power  

Only made for 2 years, 4" bore, 3.75 stroke, smaller 1.95 intake valve due to the small bore (2.08 wouldnt clear the cylinder wall) cranked out 325hp with a 4 barrel.  So i would say it was comparable to the b versions's 335 hp. The problem with the 383rb was similar to that of the 426. The bore is too small and you run into valve shrouding issues. But now we are into engine dynamics as challenger340 stated. The larger bores breathe better. And in general, the larger bores coupled with the right stroke will make big power with good heads.

The whole discussion has been fun and i have enjoyed it. Definately no hard feelings cooter!  

[Cooter]

No hard feelings. Just don't want some lower info. Person to creep up on this and think his 383 will crush his buddies 440.

With that said, the RB 383 is nothing but a heavier version of the Chevy 383 SB. Small bore, long stroke. "Dumptruck" motor.

[c00nhunterjoe]

No hard feelings. Just don't want some lower info. Person to creep up on this and think his 383 will crush his buddies 440.

With that said, the RB 383 is nothing but a heavier version of the Chevy 383 SB. Small bore, long stroke. "Dumptruck" motor.

Good point, the average guys 383 will probably have the junk cast 8:1 bottom end and think its an 11:1 mill and cant figure out why she wont go... but that goes back to the point of having the proper combination. Even the late 70's smog 440 at 8:1 was not impressive. You have to be smart and build smart.